In today's advanced semiconductor manufacturing industry, it is of critical importance to prevent contamination in all processing operations and also to detect contamination and identify the type and source of contamination as soon as possible. This applies to wet chemistry processing operations as well as all other operations used to manufacture semiconductor devices such as dry chemical processing, chemical mechanical polishing (CMP), plasma processing operations, thin film deposition operations, photolithographic operations, wafer transport operations and the like.
In wet chemical processing solutions or in other operations in which a chemical cleaning and/or rinsing solution is used, metal ion contamination in the solution must be identified as quickly as possible. The metal ion contamination in the solution contaminates and can destroy the devices being processed in the solution and metal ion contamination is also indicative of a processing problem. In addition to the metal ion contamination causing shorting or particle contamination of the device being processed in the solution, the contamination may result in ineffectiveness of the solution in carrying out its intended function. Metal ion contamination may further be indicative of a degradation of a processing tool such as the erosion of a metal part from which the metal ions emanate. This degradation can cause other equipment problems such as electrical problems and further contamination issues. If the metal ion contamination goes undetected, additional devices become contaminated as they undergo processing and the cause of the contamination may become exacerbated. The presence, extent and source of the metal ion contamination must be determined in order to eliminate the problem.
It would therefore be advantageous to detect metal ion contamination as soon as possible in order to prevent contamination of multiple devices over time and to minimize the degradation of processing equipment which can result in device misprocessing and further contamination.
Spectroscopic analytical techniques such as atomic absorption or fluorimetry are available to analyze metal ion contamination in a sampling solution. These techniques, however, are time dependent and also depend on the loading effect in the solution and human error. Moreover, the results obtained using these techniques are not real-time, in-situ results.
The present invention addresses these shortcomings of present techniques for monitoring and detecting metal ion contamination in solutions.